HVAC Refrigeration Evacuation | Technical Refrigeration - Why is it necessary to evacuate a refrigeration system before charging it with refrigerant? Because all systems are designed to operate without moisture or non-condensable gas in the system. If your air conditioner or heat pump was installed without a proper evacuation the system it will not function as designed and will likely fail prematurely. (more…)
Efficiency Factors for Condensing Units - For years compressors inside the condensing unit were sized to meet the highest load demand for whatever application they were serving. Even today, many compressors, located inside the condensing unit are sized in accordance with their highest load demand even though it is unlikely they will only be needed to run for full load conditions approximately 30-35% of the time.
While many systems have worked just fine this way for many years they have not been very energy efficient. So even on a mild day, these compressors run full blast even though the system may only require the compressor to run at 50% capacity to satisfy the demand. That creates problems with short cycling which causes premature wear, higher maintenance costs, and reduces total compressor lifespan. (more…)
Condenser Coil Repair - A crane is used here to lift a new condenser coil to a rooftop. The old condenser coil was leaking and could no longer be repaired. The process involved recovering all the refrigerant from the Trane rooftop unit.
The rooftop unit was then partially disassembled and the old coil cut out from the system taking great care and planning to ensure the new coil could be retrofitted to the old refrigeration piping system.
Good planning and skilled HVAC techs make the jobs go smoothly and make the replacement seem easy especially to the customer. (more…)
Refrigerant Pressure Temperature Chart | HVAC Refrigeration - This page offers a temperature-pressure relationship chart for use in working with HVAC Systems that use R-410A, R-22, and R-134A. Additional refrigeration information and resources are located below the chart. For more information and comprehensive articles on HVAC Refrigeration see our Refrigeration Category. (more…)
The TXV or Thermostatic Expansion Valve is preferred over other refrigeration metering devices because it only allows a specified amount of refrigerant to flow based on demand. Any type of refrigeration metering device creates a pressure drop in the refrigerant and with a pressure drop of the refrigerant a temperature drop also occurs.
This temperature is necessary to drop the refrigerant down to temperature lower than ambient temperatures inside the structure being cooled. This allows the refrigerant to absorb the heat contained in the air passing over the evaporator coil. (more…)
Superheat and Sub-cooling - In HVAC refrigeration coils and fans are used for air conditioners and heat pumps to transfer heat in one direction or another. A good HVAC technician is well versed in refrigeration. Refrigeration is defined as moving heat from one place to another. Modern air conditioners and heat pumps use a chemical refrigerant used in vapor compression refrigeration.
This chemical refrigerant has great properties for absorbing heat. What makes these chemicals so efficient is the temperature at which they change state or change from a liquid to a vapor and condense back to a liquid again. This is key to understanding superheat and subcooling. (more…)
